Effects of Si and Fe micro-additions on the aging response of a dilute Al-0.08Zr-0.08Hf-0.045Er at.% alloy

Richard A. Michi, Anthony De Luca, David N Seidman, David C Dunand

Research output: Contribution to journalArticle

Abstract

The precipitation behavior of an Al-0.08Zr-0.08Hf-0.045Er at.% alloy with micro-additions of Si and/or Fe was investigated using microhardness and electrical conductivity measurements in conjunction with scanning electron microscopy and atom-probe tomography. Hardening is achieved through the formation of a high number density (~1023 m−3) of coarsening-resistant, nanoscale L12 trialuminide precipitates containing Zr, Hf, Er, and Si. Simultaneous additions of 300 at. ppm Si and 400 at. ppm Fe produce an alloy with the fastest precipitation kinetics and highest microhardness after homogenization at 640 °C for 24 h followed by 90 days aging at 350 °C, due to: (i) scavenging of Er by Fe in the form of primary precipitates, thus reducing Er-stimulated precipitation of coarse Zr- and Hf-rich precipitates during homogenization; and (ii) the accelerating effects of Si on the precipitation kinetics of the nanometric L12 trialuminide. Removal of the homogenization step results in accelerated precipitation kinetics during aging due to an increased supersaturation of L12-forming elements, Zr, Hf, and Er. During isothermal aging of a non-homogenized Al-0.08Zr-0.08Hf-0.045Er-0.03Si-0.04Fe (at.%) alloy at 400 °C, a peak microhardness of 500 MPa is maintained for up to 90 days. Atom-probe tomography displays a high number density of nanometric L12 precipitates with an Er-rich core and homogeneously distributed Zr and Hf, with Hf concentrations ~1.5 times higher at the matrix/nanoprecipitate heterophase interface than in the core (~5 vs. ~3.5 at.%). The presence of Hf in the nanoprecipitates does not, however, affect their precipitation kinetics or coarsening resistance.

LanguageEnglish (US)
Pages72-83
Number of pages12
JournalMaterials Characterization
Volume147
DOIs
StatePublished - Jan 1 2019

Fingerprint

Precipitates
Aging of materials
Microhardness
Kinetics
precipitates
Coarsening
homogenizing
microhardness
Tomography
kinetics
Atoms
Supersaturation
Scavenging
tomography
Hardening
probes
scavenging
supersaturation
hardening
Scanning electron microscopy

Keywords

  • Al-Zr-Hf-Er alloy
  • Atom-probe tomography
  • Microhardness
  • Microstructure
  • Precipitation hardening

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

@article{d07fde2afd0043d692ecf28a725a47ea,
title = "Effects of Si and Fe micro-additions on the aging response of a dilute Al-0.08Zr-0.08Hf-0.045Er at.{\%} alloy",
abstract = "The precipitation behavior of an Al-0.08Zr-0.08Hf-0.045Er at.{\%} alloy with micro-additions of Si and/or Fe was investigated using microhardness and electrical conductivity measurements in conjunction with scanning electron microscopy and atom-probe tomography. Hardening is achieved through the formation of a high number density (~1023 m−3) of coarsening-resistant, nanoscale L12 trialuminide precipitates containing Zr, Hf, Er, and Si. Simultaneous additions of 300 at. ppm Si and 400 at. ppm Fe produce an alloy with the fastest precipitation kinetics and highest microhardness after homogenization at 640 °C for 24 h followed by 90 days aging at 350 °C, due to: (i) scavenging of Er by Fe in the form of primary precipitates, thus reducing Er-stimulated precipitation of coarse Zr- and Hf-rich precipitates during homogenization; and (ii) the accelerating effects of Si on the precipitation kinetics of the nanometric L12 trialuminide. Removal of the homogenization step results in accelerated precipitation kinetics during aging due to an increased supersaturation of L12-forming elements, Zr, Hf, and Er. During isothermal aging of a non-homogenized Al-0.08Zr-0.08Hf-0.045Er-0.03Si-0.04Fe (at.{\%}) alloy at 400 °C, a peak microhardness of 500 MPa is maintained for up to 90 days. Atom-probe tomography displays a high number density of nanometric L12 precipitates with an Er-rich core and homogeneously distributed Zr and Hf, with Hf concentrations ~1.5 times higher at the matrix/nanoprecipitate heterophase interface than in the core (~5 vs. ~3.5 at.{\%}). The presence of Hf in the nanoprecipitates does not, however, affect their precipitation kinetics or coarsening resistance.",
keywords = "Al-Zr-Hf-Er alloy, Atom-probe tomography, Microhardness, Microstructure, Precipitation hardening",
author = "Michi, {Richard A.} and {De Luca}, Anthony and Seidman, {David N} and Dunand, {David C}",
year = "2019",
month = "1",
day = "1",
doi = "10.1016/j.matchar.2018.10.016",
language = "English (US)",
volume = "147",
pages = "72--83",
journal = "Materials Characterization",
issn = "1044-5803",
publisher = "Elsevier Inc.",

}

Effects of Si and Fe micro-additions on the aging response of a dilute Al-0.08Zr-0.08Hf-0.045Er at.% alloy. / Michi, Richard A.; De Luca, Anthony; Seidman, David N; Dunand, David C.

In: Materials Characterization, Vol. 147, 01.01.2019, p. 72-83.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Effects of Si and Fe micro-additions on the aging response of a dilute Al-0.08Zr-0.08Hf-0.045Er at.% alloy

AU - Michi, Richard A.

AU - De Luca, Anthony

AU - Seidman, David N

AU - Dunand, David C

PY - 2019/1/1

Y1 - 2019/1/1

N2 - The precipitation behavior of an Al-0.08Zr-0.08Hf-0.045Er at.% alloy with micro-additions of Si and/or Fe was investigated using microhardness and electrical conductivity measurements in conjunction with scanning electron microscopy and atom-probe tomography. Hardening is achieved through the formation of a high number density (~1023 m−3) of coarsening-resistant, nanoscale L12 trialuminide precipitates containing Zr, Hf, Er, and Si. Simultaneous additions of 300 at. ppm Si and 400 at. ppm Fe produce an alloy with the fastest precipitation kinetics and highest microhardness after homogenization at 640 °C for 24 h followed by 90 days aging at 350 °C, due to: (i) scavenging of Er by Fe in the form of primary precipitates, thus reducing Er-stimulated precipitation of coarse Zr- and Hf-rich precipitates during homogenization; and (ii) the accelerating effects of Si on the precipitation kinetics of the nanometric L12 trialuminide. Removal of the homogenization step results in accelerated precipitation kinetics during aging due to an increased supersaturation of L12-forming elements, Zr, Hf, and Er. During isothermal aging of a non-homogenized Al-0.08Zr-0.08Hf-0.045Er-0.03Si-0.04Fe (at.%) alloy at 400 °C, a peak microhardness of 500 MPa is maintained for up to 90 days. Atom-probe tomography displays a high number density of nanometric L12 precipitates with an Er-rich core and homogeneously distributed Zr and Hf, with Hf concentrations ~1.5 times higher at the matrix/nanoprecipitate heterophase interface than in the core (~5 vs. ~3.5 at.%). The presence of Hf in the nanoprecipitates does not, however, affect their precipitation kinetics or coarsening resistance.

AB - The precipitation behavior of an Al-0.08Zr-0.08Hf-0.045Er at.% alloy with micro-additions of Si and/or Fe was investigated using microhardness and electrical conductivity measurements in conjunction with scanning electron microscopy and atom-probe tomography. Hardening is achieved through the formation of a high number density (~1023 m−3) of coarsening-resistant, nanoscale L12 trialuminide precipitates containing Zr, Hf, Er, and Si. Simultaneous additions of 300 at. ppm Si and 400 at. ppm Fe produce an alloy with the fastest precipitation kinetics and highest microhardness after homogenization at 640 °C for 24 h followed by 90 days aging at 350 °C, due to: (i) scavenging of Er by Fe in the form of primary precipitates, thus reducing Er-stimulated precipitation of coarse Zr- and Hf-rich precipitates during homogenization; and (ii) the accelerating effects of Si on the precipitation kinetics of the nanometric L12 trialuminide. Removal of the homogenization step results in accelerated precipitation kinetics during aging due to an increased supersaturation of L12-forming elements, Zr, Hf, and Er. During isothermal aging of a non-homogenized Al-0.08Zr-0.08Hf-0.045Er-0.03Si-0.04Fe (at.%) alloy at 400 °C, a peak microhardness of 500 MPa is maintained for up to 90 days. Atom-probe tomography displays a high number density of nanometric L12 precipitates with an Er-rich core and homogeneously distributed Zr and Hf, with Hf concentrations ~1.5 times higher at the matrix/nanoprecipitate heterophase interface than in the core (~5 vs. ~3.5 at.%). The presence of Hf in the nanoprecipitates does not, however, affect their precipitation kinetics or coarsening resistance.

KW - Al-Zr-Hf-Er alloy

KW - Atom-probe tomography

KW - Microhardness

KW - Microstructure

KW - Precipitation hardening

UR - http://www.scopus.com/inward/record.url?scp=85055743303&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85055743303&partnerID=8YFLogxK

U2 - 10.1016/j.matchar.2018.10.016

DO - 10.1016/j.matchar.2018.10.016

M3 - Article

VL - 147

SP - 72

EP - 83

JO - Materials Characterization

T2 - Materials Characterization

JF - Materials Characterization

SN - 1044-5803

ER -